There are many different image editing packages, generally I use Fireworks to edit and convert my photographs for use on the website.
One trick to use with a digital camera, is to take a long distance shot and then crop.
This is the original shot (which was 2400 x 1800 but has been resized to 600 x450 so to fit on this page).
The next stage is to decide on the area to crop, in this example I am aiming to get a picture of the Hydra.
You can now crop, so this image is in fact actual size.
Therefore you get a better result than if you tried to take the image of just the Hydra.